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Stabilization of ice creams produced with a reduced level of saturated fat

Palsgaard Technical Paper, August 2012

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Palsgaard Technical Paper - August 2012Stabilization of ice creams produced with a reduced level of saturated fat 2

In recent years there has been an increased focus on the amount of saturated fats present in food products, both from an economical point of view due to taxation on saturated fats and for health reasons. For ice cream this has put a demand on the ice cream producers to develop ice cream with a healthier profile by using more healthy ingredients or by reducing the content of the less healthy ones. This article presents the results of a study into how the emulsifiers mono- and diglycerides can help manufac-turers reduce the amount of saturated fats in ice cream.

By Claus Prior Hansen,Application Scientist, Ice Cream & Dairy Palsgaard A/S.

Fat types in ice creamFat is a key ingredient in ice cream. It plays a major role in building the internal structure of the ice cream as well as providing creaminess and smoothness. Traditionally, co-conut- and palm kernel oils have been used for the production of ice cream. These oils have a high con-tent of saturated fat - coconut 92% and palm kernel over 80%.

This high level of saturated fat gives the fats a good ability to form the internal structure of the ice cream. However, when the level of saturated fat is reduced it makes the fat softer. This makes it more challenging to produce ice cream with a good structure and the de-sired eating quality, without mak-ing adjustments in the rest of the ingredients, such as the emulsifier and stabilizer systems used.

the eFFect oF the emulsiFierThe fat and the emulsifier used in ice cream both play a role in build-ing the internal structure that sta-bilizes the ice cream. The emulsi-fier is added to reduce the stability of the ice cream emulsion. This makes it easier for the emulsion to partly break down and for the fat globules to make a partially coalesced structure once the ice cream emulsion is being whipped in the ice cream freezer.

This partially coalesced fat struc-ture stabilizes the air bubbles in-side the ice cream making the ice cream more smooth. Additionally, this partially coalesced fat struc-ture has a great influence on the melting properties of the ice cream.

setup oF studyEmulsifier and stabilizer expert Palsgaard has recently performed a study investigating the effects of different types of mono- and di-glycerides on the stabilization of ice creams with reduced levels of saturated fat. The recipe and the production methods used in this study are shown in tables 1 - 3.

In the study three different types of mono - and diglyceride systems were tested:• Fully saturated mono- and

diglycerides (Fs)• Partly unsaturated mono- and

diglycerides, containing trans fatty acids (pus-t))

• Partly unsaturated mono- and diglycerides, without trans fat-ty acids (pus-nt)

ingredient %Vegetable fat 10.00%

Skim milk powder 11.40%

Sucrose 11.50%

Glucose Syrup, 42 DE

3.35%

Stabilizer system (E410, E412)

0.16%

Mono- and diglycerides

0.40%

Water 63.20%

table 1:Ice cream recipe used

table 2:Production process

process used for the production of the ice cream mix:Mixing of all ingredients at 40°C

Homogenization: 140 bar at 75°C

Pasteurisation: 85°C for 5 sec.

Cooling to 5°C

Aging overnight at 5°C

table 3:Ice cream production

ice cream production:Continuous ice cream freezer: Gram Equipment GIF 400

Overrun: 100%

Ice cream outlet temperature: approx. -5.5°C

Hardening at -35°C for 24 hours.

Storage at -20°C

Palsgaard Technical Paper - August 2012Stabilization of ice creams produced with a reduced level of saturated fat 3

The different vegetable fats used in the study were all without trans fatty acids:• Vegetable fat with 92% satu-

rated fat (reference fat)• Vegetable fat with 50% satu-

rated fat (Fat 50)• Vegetable fat with 40% satu-

rated fat (Fat 40)

Heat Shock (HS) method:• Storage at -10°C for 4 days,

after this storage at -20°C.

The combination of the three dif-ferent mono- and diglyceride sys-tems with the three different types of fats mean that nine trials were made for this study.

analyses perFormedIn the study three different analy-ses were performed in order to evaluate the effect of the emulsi-fier:• Viscosity of aged ice cream

mix using Brookfield DV-III, spindle 2, 20 rpm

• Particle size distribution of ice cream mix after aging and of melted ice cream using Horiba LA 950

• Melting resistance of ice cream before and after heat shock. Melting was monitored for 90 minutes at 25°C.

Viscosity measurementsA mix viscosity of 300 to 500 cps was measured for the nine differ-ent ice cream mixes. Hence all nine mixes are within the common viscosity range used by the ice cream industry.

particle size distributionThe aged ice cream mixes were also subjected to a particle size distribution measurement, the responding curves can be seen across in figures 1a, 1b and 1 c.

All mixes show two peaks, at 0.1-0.5 μm and at 1-2 μm, with the main peak at 1-2 μm. For the ref-erence fat the emulsifier system

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Figure 1a:Reference fat

Figure 1b:Fat 50

Figure 1c:Fat 40

Palsgaard Technical Paper - August 2012Stabilization of ice creams produced with a reduced level of saturated fat 4

giving the narrowest particle size distribution at the main peak was pus-t.For Fat 50 all three emulsifier sys-tem gave very similar particle sizes for both peaks as indicated in fig-ure 1b, with pus-nt being slightly narrower at the main peak than the two other systems. For Fat 40, like for Fat 50, the main peaks were very similar in their particle size distribution as indicated in figure 1c, but here Fs gave the narrowest particle size distribution.

The particle size distribution of the ice cream mixes indicate that they can be used for the production of ice cream.

particle size distribution in ice creams made with Vegetable Fat with 92% saturated FatFor ice cream produced with the reference fat, there is a significant difference in the particle size distri-bution of the melted ice creams as can be seen from figure 2. The emulsifier system, Fs, gave a very narrow particle size distribu-tion compared to the two unsatu-rated emulsifier systems, indicat-ing that the unsaturated emulsifier creates a larger sized partially coa-lesced fat structure.

particle size distribution in ice creams made with Vegetable Fat with 50% saturated FatFor ice cream produced with Fat 50, there is a difference in the par-ticle size distribution for the melted ice cream as can be seen from fig-ure 3. Here as for the reference fat, the emulsifier system, Fs, gave a narrower particle size distribution compared to the two unsaturated emulsifier systems.

When comparing the main peaks of the ice creams containing the emulsifier system Fs for the refer-

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Figure 2:Reference fat - particle size distribution of melted ice cream

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Figure 3:Fat 50 - particle size distribution of melted ice cream

beneFits From switching From saturated to unsat-urated FatsSaturated fat has been linked to an increased risk of heart disease which is why the WHO recommends that the intake of saturated fat should be restricted to maximum 10% of the daily energy intake.

Reducing the amount of total fat or switching to a fat with reduced levels of saturated fat has an effect on the cost of the final ice cream in countries where there is a taxation on the amount of saturated fat in the ice cream like in Denmark. As an example the Danish tax is 16 DKK + 25% VAT per kg of saturated fat.

Palsgaard Technical Paper - August 2012Stabilization of ice creams produced with a reduced level of saturated fat 5

ence fat and Fat 50, it can be seen that the particle size distribution of the reference fat are smaller than for Fat 50, indicating that the com-bination of the emulsifier system Fs and Fat 50 are better at making a partially coalesced fat structure.The ice creams containing the two unsaturated emulsifiers are again containing particles of a larger size. This indicates that these emulsifiers are better at making larger sized partially coalesced fat structures.

particle size distribution in ice creams made with Vegetable Fat with 40% saturated FatIce creams produced with Fat 40, have similar particle size distribu-tion with the emulsifier systems Fs and pus-t, whereas the emulsifier system pus-nt creates larger par-ticles than the two other systems as shown in figure 4.

testing the melting resist-ance oF ice creams made with Vegetable Fat with 92% saturated FatThe melting resistance of the ice creams produced with the refer-ence fat, is strongly influenced by the type of emulsifier used. This is evident when looking at figure 5. Ice creams made using the emul-sifier system Fs loose 25-30% of its weight after 90 min, whereas the ice creams made with the un-saturated emulsifier systems only loose up to 5% after 90 min. This correlates well with the particle size distribution of the ice creams produced with the reference fat as discussed earlier. The unsaturated emulsifier systems gave much larger particles than the emulsifier system Fs as indicated in figure 2.

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Figure 4:Fat 40 - particle size distribution of melted ice cream

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Figure 5:Reference fat - melting resistance

Palsgaard Technical Paper - August 2012Stabilization of ice creams produced with a reduced level of saturated fat 6

testing the melting resist-ance oF ice creams made with Vegetable Fat with 50% saturated FatsThe melting resistance of the ice creams made with Fat 50, are very similar, as can be seen from figure 6. All the ice creams loose up to 5% of their weight after 90 min.

From the results of the particle size distribution of the ice creams shown in figure 3 one would expect that the combination of Fat 50 and emulsifier system Fs would offer the least melting resistance. This is due to the more narrow particle size distribution of the ice creams made with Fs than with the unsat-urated emulsifier systems.

However, as this is not the case this could indicate that the ability to make a partially coalesced fat structure in the ice cream is less sensitive to the type of emulsifier used in combination with Fat 50.

testing the melting resist-ance oF ice creams made with Vegetable Fat with 40% saturated FatsThe melting resistance of the ice creams made with Fat 40 are in-fluenced by the type of emulsifier used. The ice creams produced with pus-nt loose up to 12% of their weight after 90 min. Where-as the ice creams produced with emulsifier systems Fs and pus-t only loose up to 5% after 90 min - as indicated in figure 7. When comparing these results with the particle size distribution for Fat 40 discussed earlier, it would be ex-pected that these ice creams gave very similar melting resistances. However, the fact that pus-nt of-fered the least melting resistance, but had the largest particles, as can be seen in figure 4, could indi-cate that these partially coalesced fat structures are more coalesced and therefore not participating in building the internal structure if the ice cream.

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Figure 6:Fat 50 - melting resistance

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Figure 7:Fat 40 - melting resistance

Palsgaard Technical Paper - August 2012Stabilization of ice creams produced with a reduced level of saturated fat 7

conclusionBased on this study it can be con-cluded that an adjustment of the mono- and diglyceride systems used in production of ice cream will have to be considered when switching to fats with a lower amount of saturated fats.

Palsgaard will be pleased to assist you in selecting the right mono- and diglyceride system for your requirements be it for a new prod-uct or for reformulating an existing product in order to adhere to con-sumer requests for healthier ice creams.

The emulsifier systems used in this study are part of the in-tegrated emulsifier and stabi-lizer blends within the product ranges Palsgaard® ExtruIce and Palsgaard® MouldIce.

about palsgaardPalsgaard is a specialist in devel-oping emulsifiers and stabilizer blends for various types of ice cream ranging from moulded to ex-truded ice cream and sorbets and water ices. With application plants on three continents Palsgaard also helps its customers develop new products or optimize existing for-mulations.

Palsgaard’s application centres are fully equipped with continuous ice cream pilot freezers, two-stage homogenizers and pasteurization units. Which is why the company is capable of simulating every single processing step of a real size pro-duction facility.

For more information on this study, please contact: Application Scientist Claus Prior Hansen at cph@palsgaard.dk or Tel +45 7682 7682